This is the complete Rig Veda in English. The core scriptures of Hinduism are the four Vedas: Rig, Yajur, Sama, and Atharvana. Each of the four Vedas has four parts: Samhitas, Brahmanas, Aranyakas, and Upanishads. Yet usually when you see a book called "Rig Veda", it just means the Rig Veda Samhita. That's what I intend to remedy with this document; this is the complete Rig Veda with Samhita, Brahmanas, Aranyaka, and Upanishad portions.
One more thing: each Veda comes in multiple Shakhas or recensions. The Rig Veda used to have 21 Shakhas, but now only two Shakhas survive: the Bashala Shakha and the Sakala Shakha. What is presented here is the Sakala Shakha's version of the Rig Veda. I created it by putting together Ralph T.H. Griffith's translation of (the Sakala Shakha's version of) the Rig Veda Samhita with Arthur Berriedale Keith's translations of the Aitareya Brahmana and Aitareya Aranyaka of the Rig Veda. (The Aitareya Upanishad is contained in the Aitareya Aranyaka.) I would have made it in the Bashkala Shakha as well, by combining the Bashkala Shakha's version of the Rig Veda Samhita with the Kaushitaki Brahmana and Shankhayana Aranyaka of the Rig Veda, but as far as I know there's never been an English translation of the Bashakala Shakha's version of the Rig Veda Samhita.
By the way, if you're interested in this sort of thing you should check out the site Hinduism Stack Exchange: http://hinduism.stackexchange.com